The present invention relates broadly to a binary word generator apparatus, and in particular to a variable data base generator apparatus.
In many fields of scientific endeavor, situations exist that require a source of random numbers. One typical example is simulating actual operating conditions while testing a piece of apparatus. In this case, a series of random numbers might represent different operating conditions.
Commonly, random numbers in binary form are generated in digital computers by the so-called multiplicative-congruential methods. These methods, however, yield numbers that are only random in the higher denominational order bit positions.
Random numbers can be formed by the accumulation of random bits in a shift register. Each random bit is derived from a random noise voltage. A random number is thus obtained with a single input operation--much faster than with an algorithmic generator. However, this simple scheme develops random numbers having nonideal statistical properties because the circuits used are not ideal. Unavoidable unbalance in the sampler circuits will introduce a bias in the random bits. In addition, correlation between neighboring bits could result from a limited noise bandwidth as well as sampler hysteresis. There exist methods which are used to eliminate the bias of random bits. However, in these older methods the choice between one or the other value for a given bit is influenced by an average of values of bits previously produced. The introduction of said average leads to undesired long-term correlations.